Writing a book
Maybe you can add a challenge about writing a book. Which is the famous one. Or one of chapter from it. We can create a party and all of us will try to write it in time. We can play against party versus party or you can show the top 50 fastest parties ever.. something like that.
With doing that section. Users will read that book's part and if they like it; they will buy and read all of it. You can also take some advertisement from new books. Thus we will see how beatiful a new book is. :)
-My kindly regards.